\begin{tikzpicture}
    \begin{scope}[xshift=-2cm]
        \tkzDefPoints{0/0/A, 1/0/B, 1/1/C, 0/1/D}
        \tkzDrawPolygon(A,B,C,D)
        \tkzLabelSegment[below](A,B){$1$}
        \tkzLabelSegment[right](B,C){$1$}
    \end{scope}

    \begin{scope}
        \tkzDefPoints{0/0/A, 7/0/B, 5/4/C, 0/4/D}
        \tkzClipPolygon(A,B,C,D)
        \foreach \x in {0,...,7} {
            \tkzDefPoints{\x/0/X1, \x/4/X2}
            \tkzDrawSegments(X1,X2)
        }
        \foreach \y in {0,...,4} {
            \tkzDefPoints{0/\y/Y1, 7/\y/Y2}
            \tkzDrawSegments(Y1,Y2)
        }
        \tkzDrawPolygon[very thick](A,B,C,D)
    \end{scope}
\end{tikzpicture}

